<div dir="ltr"><div>Dear all, </div><div><br></div><div>I thought I should post an update on this. </div><div><br></div><div>It seems that there is a problem with using PW92 as the local correlation part of XC functional. When I use VWN instead, the analytical and numerical forces are equal. I attach input and output files for DEBUG runs on a single H20 molecule using optPBE in combination with PW92 and VWN. In the case of PW92, there is a mismatch between analytical and numerical forces. </div><div><br></div><div>I note that the same applies for the some of the other functionals listed here: <a href="https://github.com/cp2k/cp2k/tree/master/data/xc_section">https://github.com/cp2k/cp2k/tree/master/data/xc_section</a> (at least, I can confirm that optB88 and C09 also give a mismatch between numerical and analytical forces using the settings listed here). </div><div><br></div><div>Best wishes, </div><div><br></div><div>Jan</div><div><br></div><div><br></div><br><br>On Friday, April 24, 2020 at 10:43:00 AM UTC+1, Jan Elsner wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr">Dear Juerg, <div><br></div><div>Many thanks for the quick response! Unfortunately, decreasing EPS_SCF (all the way to 1.0E-10) does not solve the problem. </div><div><br></div><div>I have done a DEBUG run which results in the following error (see end of attached file debug.out): <b>'Abort: A mismatch between the analytical and the numerical stress tensor has been detected. Check the implementation of the stress tensor'</b>. I'm not entirely sure how I should proceed from here / what the problem is exactly - any insight would be very much appreciated. </div><div><br></div><div>If it helps shed some light on the problem, I also attach a figure showing Total Energy, RMS Gradient and Cell Volume as a function of optimization step (plotted from the original cell.out file I sent). The optimiser seems to overshoot the minimum energy configuration. </div><div><br></div><div>One other question which comes to mind is whether it's ok to use GTH-PBE or GTH-PADE pseudopotentials with optPBE-vdW?</div><div><br></div><div>Best wishes, <br><br>Jan</div><div><br></div><div><br></div><div><br></div><div><br><br>On Monday, April 20, 2020 at 10:20:34 AM UTC+1, jgh wrote:<blockquote class="gmail_quote" style="margin:0;margin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex">Hi
<br>
<br>I don't know how well a setup as this is tested. However, from
<br>your output I would guess the problem could be related to your
<br>SCF convergence. With the methods you are using you have to set
<br>the convergence criteria much tighter in order to get converged
<br>energy and forces. I would suggest to use at least 1.E-8.
<br>
<br>The ultimate test would be to do a DEBUG run in order to verify
<br>forces and stress tensor for the setting of options.
<br>
<br>regards
<br>
<br>Juerg Hutter
<br>------------------------------<wbr>------------------------------<wbr>--
<br>Juerg Hutter Phone : ++41 44 635 4491
<br>Institut für Chemie C FAX : ++41 44 635 6838
<br>Universität Zürich E-mail: <a rel="nofollow">h...@chem.uzh.ch</a>
<br>Winterthurerstrasse 190
<br>CH-8057 Zürich, Switzerland
<br>------------------------------<wbr>------------------------------<wbr>---
<br>
<br>-----<a rel="nofollow">c...@googlegroups.com</a> wrote: -----
<br>To: "cp2k" <<a rel="nofollow">c...@googlegroups.com</a>>
<br>From: "Jan Elsner"
<br>Sent by: <a rel="nofollow">c...@googlegroups.com</a>
<br>Date: 04/18/2020 08:33PM
<br>Subject: [CP2K:13145] CELL Optimization - Energy not decreasing
<br>
<br>Dear all,
<br>
<br>I am trying to run a Cell Optimisation on a periodic molecular crystal (beta-resorcinol: C6H6O2, 4 molecules in unit cell) using K-points and BFGS as optimiser. I am using the vdW-DF-optPBE functional (<a href="https://github.com/cp2k/cp2k/commit/74ef05b96a46523a0daf7da04e75804420b5cd5e" rel="nofollow" target="_blank" onmousedown="this.href='https://www.google.com/url?q\x3dhttps%3A%2F%2Fgithub.com%2Fcp2k%2Fcp2k%2Fcommit%2F74ef05b96a46523a0daf7da04e75804420b5cd5e\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNFJFdDtTdkHeDG9Vkx91Y3xAmjbtQ';return true;" onclick="this.href='https://www.google.com/url?q\x3dhttps%3A%2F%2Fgithub.com%2Fcp2k%2Fcp2k%2Fcommit%2F74ef05b96a46523a0daf7da04e75804420b5cd5e\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNFJFdDtTdkHeDG9Vkx91Y3xAmjbtQ';return true;">https://github.com/cp2k/cp2k/<wbr>commit/<wbr>74ef05b96a46523a0daf7da04e7580<wbr>4420b5cd5e</a>). After 83 optimisation steps, my system does converge to the required MOTION thresholds, however from step 7 onwards the total energy increases at every step i.e.:
<br>
<br>-------- Informations at step = 7 ------------
<br> Optimization Method = BFGS
<br> Total Energy = -280.1489665596
<br> Internal Pressure [bar] = -2667.4573178334
<br> Real energy change = 0.0001037473
<br> Predicted change in energy = -0.0001063956
<br> Scaling factor = 0.0000000000
<br> Step size = 0.0124910496
<br> Trust radius = 0.4724315332
<br> Decrease in energy = NO
<br> Used time = 60.978
<br>
<br> Convergence check :
<br> Max. step size = 0.0124910496
<br> Conv. limit for step size = 0.0010000000
<br> Convergence in step size = NO
<br> RMS step size = 0.0029192108
<br> Conv. limit for RMS step = 0.0010000000
<br> Convergence in RMS step = NO
<br> Max. gradient = 0.0034738629
<br> Conv. limit for gradients = 0.0001000000
<br> Conv. for gradients = NO
<br> RMS gradient = 0.0006857738
<br> Conv. limit for RMS grad. = 0.0001000000
<br> Conv. for gradients = NO
<br> Pressure Deviation [bar] = -2668.4705678334
<br> Pressure Tolerance [bar] = 200.0000000000
<br> Conv. for PRESSURE = NO
<br> -----------------------------<wbr>----------------------
<br>
<br>The resulting cell-optimised structure is therefore not a minimum in energy. I've attached the input and output files. Some points which may (or may not) be relevant:
<br>I did not encounter this problem when using a different functional (PBE + D3 instead of optPBE-vdW as used here), but otherwise identical settings.
<br>I encountered the same issue (energy increasing at every step) using CUTOFF/REL_CUTOFF = 800/60
<br>I initially tried to converge CUTOFF and REL_CUTOFF as in the tutorial (
<br><a href="https://www.cp2k.org/howto:converging_cutoff" rel="nofollow" target="_blank" onmousedown="this.href='https://www.google.com/url?q\x3dhttps%3A%2F%2Fwww.cp2k.org%2Fhowto%3Aconverging_cutoff\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNFHeI16YFpXApR5fGmB8YOPSHi7nQ';return true;" onclick="this.href='https://www.google.com/url?q\x3dhttps%3A%2F%2Fwww.cp2k.org%2Fhowto%3Aconverging_cutoff\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNFHeI16YFpXApR5fGmB8YOPSHi7nQ';return true;">https://www.cp2k.org/howto:<wbr>converging_cutoff</a>), however my single point calculations did not converge quite as nicely as in the tutorial - instead oscillating with an amplitude of order ~ e-4 Ha (I've attached a figure showing this). This is why I use such large CUTOFF/REL_CUTOFF values. I note that this was also the case when I ran PBE + D3 calculations, however in the latter case my cell optimisation did work.
<br>
<br>Any input would be greatly appreciated.
<br>
<br>Best wishes,
<br>
<br>Jan
<br>
<br>
<br>
<br> --
<br> You received this message because you are subscribed to the Google Groups "cp2k" group.
<br> To unsubscribe from this group and stop receiving emails from it, send an email to <a rel="nofollow">c...@googlegroups.com</a>.
<br> To view this discussion on the web visit <a href="https://groups.google.com/d/msgid/cp2k/e97788c6-1c43-453d-893e-6b973a977f9d%40googlegroups.com" rel="nofollow" target="_blank" onmousedown="this.href='https://groups.google.com/d/msgid/cp2k/e97788c6-1c43-453d-893e-6b973a977f9d%40googlegroups.com';return true;" onclick="this.href='https://groups.google.com/d/msgid/cp2k/e97788c6-1c43-453d-893e-6b973a977f9d%40googlegroups.com';return true;">https://groups.google.com/d/<wbr>msgid/cp2k/e97788c6-1c43-453d-<wbr>893e-6b973a977f9d%<wbr>40googlegroups.com</a>.
<br>
<br>
<br>[attachment "cell.inp" removed by Jürg Hutter/at/UZH]
<br>[attachment "cell.out" removed by Jürg Hutter/at/UZH]
<br>[attachment "E_vs_cutoff.png" removed by Jürg Hutter/at/UZH]
<br>[attachment "subsys.include" removed by Jürg Hutter/at/UZH]
<br></blockquote></div></div></blockquote></div>